In numerous industries, including the telecommunications industry, the automotive industry, and the computer industry, applications exist which require high power digital switching, analog amplification, and digital logic circuitry. In many such applications, placing all the required circuitry onto a single integrated circuit chip would result in improved performance and miniaturization if an adequately reliable and adequately inexpensive single chip could be produced.
In the disk drive industry today, for example, disk drive controllers are often realized in multiple chip implementations. Problems associated with integrating the power transistors and the digital logic transistors of the disk drive controller result in the DMOS power circuitry being placed on one chip whereas the CMOS digital logic circuitry is placed on another chip. Similarly, the analog amplification circuitry of the disk drive controller may be placed on yet a third chip due to the difficulty of producing a single circuit die which incorporates both high quality bipolar analog amplifiers and also high performance CMOS digital logic and/or DMOS power transistors. Accordingly, a process is sought which allows DMOS power circuitry, CMOS digital logic circuitry, and complementary bipolar analog circuitry all to be realized on a single integrated circuit chip.